GENOTYPE x ENVIRONMENT INTERACTION AND YIELD STABILITY OF MAIZE VARIETIES UNDER CONTRASTING PHOSPHORUS CONDITIONS

The low productivity of maize (Zea mays L.) on the P'urhepecha Plateau, Mexico, is caused by soil acidity and phosphorus deficiency. To increase productivity, it is necessary to develop high-yielding varieties that are stable in acid soils. The objective of this study was to estimate the effect of the interaction genotype x environment (IGA) on maize yield and its degree of stability in different agroecological conditions. We assessed yield of 25 native maize genotypes and two controls cultivated in five localities of the P'urhepecha Plateau with acid soils deficient in phosphorus fertilized with low (BP) (25 kg P2O5 ha(-1)) and high (AP) (50 kg P2O5 ha(-1)) dosages of fertilization. The Additive Main Effects and Multiplicative Interaction (AMMI) and the site regression (SREG) methods were used to study the interaction genotype x environment (IGA) and define environments that better discriminate genotypes and allow grouping of environments and genotypes. The AMMI analysis identified the localities of Erongaricuaro in the environments of AP (ERA) and BP (ERB) as the greatest interaction and the genotypes Paso del Muerto 1 [109], Santa Clara [115], DP x Tronmba [127], Macho II-04 [230], Macho-I-04 [236], and the local race as the most stable with good yield in AP and BP. The SREG method determined the relative performance of the genotypes in a specific environment and identified the best genotypes across environments with similar characteristics. Based on the AMMI stability value (ASV) and the genotype selection index (GSI), the most stable genotypes with the highest grain yield in the environments assessed were DP x Tromba [127], Macho-I-04 [236] and Santa Clara [115]. These genotypes exhibited phenotypical stability for yield in acid soils deficient in phosphorus.